1. Field of the Invention
This invention relates to switching a volume address association and more particularly relates to switching a volume address association in a point-in-time copy relationship.
2. Description of the Related Art
Data processing devices (“DPD”) such as mainframe computers, servers, computer workstations, laptop computers, portable digital assistants, embedded processing nodes, and the like often store data to and retrieve data from a storage device. The storage device may be a hard disk drive, an optical storage device, a micromechanical storage device, a semiconductor storage device, or the like. A plurality of storage devices may be organized as a storage system.
A DPD may store data to and retrieve data from a logical volume of a storage system and/or a storage device. The logical volume may comprise portions of one or more storage devices. In addition, the logical volume may appear to the DPD as a single logical storage device. For example, a server DPD may access data from a logical volume organized as four hard disk drives of a storage system, wherein the logical volume appears to the server as a single storage device.
The data stored in the logical volume is often very valuable. Unfortunately, the data may be lost due to corruption. Storage device failure, invalid transactions, write errors, and software viruses may corrupt data. As a result, a DPD and/or storage system may frequently backup the data of the logical volume to protect the data. For example, the data of a source logical volume, herein referred to as a source volume, may be copied to a target logical volume, herein referred to as a target volume, as a flash copy such as by using the FlashCopy® Solutions software from International Business Machines Corporation (“IBM”) of Armonk, N.Y. The flash copy is a point-in-time instance of the source volume data.
If the source volume data becomes corrupted before the full copy from the source volume to the target volume has completed, the copy to the target volume must be completed before data can be recovered to the source volume. Unfortunately, recovering data by copying the data from the source volume to the target volume may be a lengthy process, particularly for source volumes that store significant amounts of data. While completing the copy to the target volume, the point in time version of the source volume data is unavailable at the source volume. The data recovery process may take many hours, during which time the DPD and/or storage system may be unable to access needed data. The loss of data access can be expensive, particularly in transaction and data intensive enterprise applications.
Alternatively, an administrator may change the DPD configuration to access the target volume, which is time consuming and error prone. After copying all data to the target volume, and then doing another flash copy back to the source volume, the DPD has access to the source volume with valid data while the target volume to source volume flash copy completes.
From the foregoing discussion, it should be apparent that a need exists for an apparatus, system, and method that support rapid access to point-in-time copies of data. Beneficially, such an apparatus, system, and method would speed the recovery process for corrupted data.